While an electric vehicle's range on a charge is arguably its most critical specification – after all, nobody wants to wind up stranded at the side of the road with a depleted battery – its operating efficiency should come in at a close second.

To help consumers compare the energy consumption of electric cars with those that run on fossil fuel, the EPA created a miles-per-gallon equivalent measurement, called "MPGe." This is calculated based on a conversion factor of 33.705 kilowatt-hours of electricity equaling one gallon of gasoline.

But be aware that the EVs boasting the longest range on a charge are not necessarily the most electricity-efficient. For example, though the new-for-2019 Jaguar i-Pace is rated to run for a stellar 234 miles with a full charge, it's the least efficient EV among 2019 models in terms of its kilowatt consumption. The Environmental Protection Agency rates the i-Pace at 76 MPGe in combined city/highway driving. While that handily beats any internal combustion vehicle, it trails the electric competition considerably.